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<!DOCTYPE html>
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<meta charset="utf-8">
<title>JSDoc: Source: entry.js</title>
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<h1 class="page-title">Source: entry.js</h1>
<section>
<article>
<pre class="prettyprint source linenums"><code>'use strict'
const Clock = require('./lamport-clock')
const { isDefined, io } = require('./utils')
const stringify = require('json-stringify-deterministic')
const IpfsNotDefinedError = () => new Error('Ipfs instance not defined')
const IPLD_LINKS = ['next', 'refs']
const getWriteFormatForVersion = v => v === 0 ? 'dag-pb' : 'dag-cbor'
const getWriteFormat = e => Entry.isEntry(e) ? getWriteFormatForVersion(e.v) : getWriteFormatForVersion(e)
/*
* @description
* An ipfs-log entry
*/
class Entry {
/**
* Create an Entry
* @param {IPFS} ipfs An IPFS instance
* @param {Identity} identity The identity instance
* @param {string} logId The unique identifier for this log
* @param {*} data Data of the entry to be added. Can be any JSON.stringifyable data
* @param {Array<string|Entry>} [next=[]] Parent hashes or entries
* @param {LamportClock} [clock] The lamport clock
* @returns {Promise<Entry>}
* @example
* const entry = await Entry.create(ipfs, identity, 'hello')
* console.log(entry)
* // { hash: null, payload: "hello", next: [] }
*/
static async create (ipfs, identity, logId, data, next = [], clock, refs = [], pin) {
if (!isDefined(ipfs)) throw IpfsNotDefinedError()
if (!isDefined(identity)) throw new Error('Identity is required, cannot create entry')
if (!isDefined(logId)) throw new Error('Entry requires an id')
if (!isDefined(data)) throw new Error('Entry requires data')
if (!isDefined(next) || !Array.isArray(next)) throw new Error("'next' argument is not an array")
// Clean the next objects and convert to hashes
const toEntry = (e) => e.hash ? e.hash : e
const nexts = next.filter(isDefined).map(toEntry)
const entry = {
hash: null, // "zd...Foo", we'll set the hash after persisting the entry
id: logId, // For determining a unique chain
payload: data, // Can be any JSON.stringifyable data
next: nexts, // Array of hashes
refs: refs,
v: 2, // To tag the version of this data structure
clock: clock || new Clock(identity.publicKey)
}
const signature = await identity.provider.sign(identity, Entry.toBuffer(entry))
entry.key = identity.publicKey
entry.identity = identity.toJSON()
entry.sig = signature
entry.hash = await Entry.toMultihash(ipfs, entry, pin)
return entry
}
/**
* Verifies an entry signature.
*
* @param {IdentityProvider} identityProvider The identity provider to use
* @param {Entry} entry The entry being verified
* @return {Promise} A promise that resolves to a boolean value indicating if the signature is valid
*/
static async verify (identityProvider, entry) {
if (!identityProvider) throw new Error('Identity-provider is required, cannot verify entry')
if (!Entry.isEntry(entry)) throw new Error('Invalid Log entry')
if (!entry.key) throw new Error("Entry doesn't have a key")
if (!entry.sig) throw new Error("Entry doesn't have a signature")
const e = Entry.toEntry(entry, { presigned: true })
const verifier = entry.v < 1 ? 'v0' : 'v1'
return identityProvider.verify(entry.sig, entry.key, Entry.toBuffer(e), verifier)
}
/**
* Transforms an entry into a Buffer.
* @param {Entry} entry The entry
* @return {Buffer} The buffer
*/
static toBuffer (entry) {
const stringifiedEntry = entry.v === 0 ? JSON.stringify(entry) : stringify(entry)
return Buffer.from(stringifiedEntry)
}
/**
* Get the multihash of an Entry.
* @param {IPFS} ipfs An IPFS instance
* @param {Entry} entry Entry to get a multihash for
* @returns {Promise<string>}
* @example
* const multihash = await Entry.toMultihash(ipfs, entry)
* console.log(multihash)
* // "Qm...Foo"
* @deprecated
*/
static async toMultihash (ipfs, entry, pin = false) {
if (!ipfs) throw IpfsNotDefinedError()
if (!Entry.isEntry(entry)) throw new Error('Invalid object format, cannot generate entry hash')
// // Ensure `entry` follows the correct format
const e = Entry.toEntry(entry)
return io.write(ipfs, getWriteFormat(e.v), e, { links: IPLD_LINKS, pin })
}
static toEntry (entry, { presigned = false, includeHash = false } = {}) {
const e = {
hash: includeHash ? entry.hash : null,
id: entry.id,
payload: entry.payload,
next: entry.next
}
const v = entry.v
if (v > 1) {
e.refs = entry.refs // added in v2
}
e.v = entry.v
e.clock = new Clock(entry.clock.id, entry.clock.time)
if (presigned) {
return e // don't include key/sig information
}
e.key = entry.key
if (v > 0) {
e.identity = entry.identity // added in v1
}
e.sig = entry.sig
return e
}
/**
* Create an Entry from a hash.
* @param {IPFS} ipfs An IPFS instance
* @param {string} hash The hash to create an Entry from
* @returns {Promise<Entry>}
* @example
* const entry = await Entry.fromMultihash(ipfs, "zd...Foo")
* console.log(entry)
* // { hash: "Zd...Foo", payload: "hello", next: [] }
*/
static async fromMultihash (ipfs, hash) {
if (!ipfs) throw IpfsNotDefinedError()
if (!hash) throw new Error(`Invalid hash: ${hash}`)
const e = await io.read(ipfs, hash, { links: IPLD_LINKS })
const entry = Entry.toEntry(e)
entry.hash = hash
return entry
}
/**
* Check if an object is an Entry.
* @param {Entry} obj
* @returns {boolean}
*/
static isEntry (obj) {
return obj && obj.id !== undefined &&
obj.next !== undefined &&
obj.payload !== undefined &&
obj.v !== undefined &&
obj.hash !== undefined &&
obj.clock !== undefined &&
(obj.refs !== undefined || obj.v < 2) // 'refs' added in v2
}
/**
* Compares two entries.
* @param {Entry} a
* @param {Entry} b
* @returns {number} 1 if a is greater, -1 is b is greater
*/
static compare (a, b) {
const distance = Clock.compare(a.clock, b.clock)
if (distance === 0) return a.clock.id < b.clock.id ? -1 : 1
return distance
}
/**
* Check if an entry equals another entry.
* @param {Entry} a
* @param {Entry} b
* @returns {boolean}
*/
static isEqual (a, b) {
return a.hash === b.hash
}
/**
* Check if an entry is a parent to another entry.
* @param {Entry} entry1 Entry to check
* @param {Entry} entry2 The parent Entry
* @returns {boolean}
*/
static isParent (entry1, entry2) {
return entry2.next.indexOf(entry1.hash) > -1
}
/**
* Find entry's children from an Array of entries.
* Returns entry's children as an Array up to the last know child.
* @param {Entry} entry Entry for which to find the parents
* @param {Array<Entry>} values Entries to search parents from
* @returns {Array<Entry>}
*/
static findChildren (entry, values) {
let stack = []
let parent = values.find((e) => Entry.isParent(entry, e))
let prev = entry
while (parent) {
stack.push(parent)
prev = parent
parent = values.find((e) => Entry.isParent(prev, e))
}
stack = stack.sort((a, b) => a.clock.time > b.clock.time)
return stack
}
}
module.exports = Entry
module.exports.IPLD_LINKS = IPLD_LINKS
module.exports.getWriteFormat = getWriteFormat
</code></pre>
</article>
</section>
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<h2><a href="index.html">Home</a></h2><h3>Classes</h3><ul><li><a href="GSet.html">GSet</a></li><li><a href="Log.html">Log</a></li></ul><h3>Global</h3><ul><li><a href="global.html#LastWriteWins">LastWriteWins</a></li><li><a href="global.html#NoZeroes">NoZeroes</a></li><li><a href="global.html#SortByClockId">SortByClockId</a></li><li><a href="global.html#SortByClocks">SortByClocks</a></li><li><a href="global.html#SortByEntryHash">SortByEntryHash</a></li></ul>
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